Water Resources NILAY PATEL ( ) PARTH PATEL ( )

n Hydrosphere: All the water at or near the surface of the earth n Amount of water essentially constant and moves between different reservoirs n 100 million billion gallons move through Hydrologic Cycle n Oceans account for ~96%, Fresh water lakes and streams for only 0.016% of all water Hydrologic Cycle

Distribution of Water

Thousands of km 3 /yr Hydrologic Cycle

Ground water 22% of all fresh water occur underground 22% of all fresh water occur underground Aquifer: Underground formation that holds and yields water Aquifer: Underground formation that holds and yields water A good aquifer needs to be both porous and permeable A good aquifer needs to be both porous and permeable

Porosity and Permeability Porosity: Proportion of void space: pore space, cracks, vesicles Porosity: Proportion of void space: pore space, cracks, vesicles Gravel : 25-45% (1K - 10K), Clay: 45-55%(<.01)Gravel : 25-45% (1K - 10K), Clay: 45-55%(<.01) sandstone: 5-30% ( ), Granite: <1 to 5%(.003 to.00003)sandstone: 5-30% ( ), Granite: <1 to 5%(.003 to.00003) higher porosity in well rounded, equigranular, coarse grained rockshigher porosity in well rounded, equigranular, coarse grained rocks Permeability: Measure of how readily fluid passes through a material Permeability: Measure of how readily fluid passes through a material Depends on the size of the pores and how well they are interconnectedDepends on the size of the pores and how well they are interconnected Clay has high porosity but low permeabiltyClay has high porosity but low permeabilty

Less porosity porositypermeability Clay 45-55%<0.01 m/day sand30-52% gravel %1000 to 10,000

Subsurface Water Zone of Aeration or Vadose Zone or Unsaturated Zone: Overlies Phreatic Zone. Pore spaces partly filled with water. Contains soil moisture. Zone of Aeration or Vadose Zone or Unsaturated Zone: Overlies Phreatic Zone. Pore spaces partly filled with water. Contains soil moisture. Saturated Zone n Zone of Saturation or Phreatic Zone: saturated zone overlying impermeable bed rock. Water fills all the available pore spaces n Water Table: top of the zone of saturation where not confined by impermeable rock

Water table follows the topography but more gently Water table follows the topography but more gently Intersection of water table and ground surface produces lakes, streams, spring, wetlands… Intersection of water table and ground surface produces lakes, streams, spring, wetlands… Ground water flows from higher elevation to lower, from areas of lower use to higher use, from wet areas to dry areas. Ground water flows from higher elevation to lower, from areas of lower use to higher use, from wet areas to dry areas.

Darcy’s law Hydraulic Gradient: Slope of the ground water table Hydraulic Gradient: Slope of the ground water table Rate of flow is proportional to the hydraulic gradient Rate of flow is proportional to the hydraulic gradient

Aquifer Recharge: Process of replenishment of Ground Water by infiltration, migration and percolation Recharge: Process of replenishment of Ground Water by infiltration, migration and percolation Aquifer: A rock that holds enough water and transmits it rapidly. Porous and Permeable. Sandstone and Coarse Clastic Sedimentary rocks make good aquifers Aquifer: A rock that holds enough water and transmits it rapidly. Porous and Permeable. Sandstone and Coarse Clastic Sedimentary rocks make good aquifers Aquitard and Aquiclude: Rocks of low and very low permeability e.g., shale, slate Aquitard and Aquiclude: Rocks of low and very low permeability e.g., shale, slate Perched water table: Local aquifer in Vadose Zone Perched water table: Local aquifer in Vadose Zone

Confined and Unconfined Aquifer Unconfined Aquifer: open to atmosphere e.g., overlain by permeable rocks and soils Unconfined Aquifer: open to atmosphere e.g., overlain by permeable rocks and soils Confined aquifer: sandwiched between aquitards Confined aquifer: sandwiched between aquitards Artesian System: Water rises above the level in aquifer because of hydrostatic pressureArtesian System: Water rises above the level in aquifer because of hydrostatic pressure Potentiometric surface: Height to which water pressure would raise the water. Potentiometric surface: Height to which water pressure would raise the water.

Artesian System: Water rises above the level in aquifer because of hydrostatic pressure Potentiometric surface: Height to which water pressure would raise the water.

Consequences of Ground Water Withdrawal –overlapping cones of depression causes lowering of regional water table –Water mining: rate of recharge too slow for replenishment in human life time

Consequences of Ground Water Withdrawal…. Compaction and Subsurface subsidence Compaction and Subsurface subsidence Building damage, collapseBuilding damage, collapse flooding and coastal erosion e.g., Venice, Galveston/Houston (80 sq km permanently flooded), San Joaquin Valley (9m subsidence)flooding and coastal erosion e.g., Venice, Galveston/Houston (80 sq km permanently flooded), San Joaquin Valley (9m subsidence) Pumping in of water no solutionPumping in of water no solution

Changes in ground- water levels in the High Plains aquifer from before ground-water development to (V.L. McGuire, U.S. Geological Survey, written commun., 1998.)

Land subsidence in Houston

Salt water incursion in caostal aquifer n Saltwater Intrusion –upconing below cone of depression –Aquifer below Brooklyn, NY destroyed –Serious problem in Gulf Coast and California

Sinkholes Sinkholes forms in areas with abundant water and soluble bedrock (gypsum or limestone)forms in areas with abundant water and soluble bedrock (gypsum or limestone) collapse follows ground water withdrawalcollapse follows ground water withdrawal

Interfering with the flood plain Asphalt and concrete reduces infiltration and hence the lag time Asphalt and concrete reduces infiltration and hence the lag time Buildings in the flood plain increases flood heights (why?) Buildings in the flood plain increases flood heights (why?) Storm sewers quicken the flow to the river Storm sewers quicken the flow to the river Exposed soils silt up the river channel Exposed soils silt up the river channel

Reducing Flood Hazards Retention ponds Retention ponds does not alter the channel, can be farmeddoes not alter the channel, can be farmed Channelization Channelization Mississippi case history, Florida problems, Export of floodingMississippi case history, Florida problems, Export of flooding Levees (Raised banks along the channel) Levees (Raised banks along the channel) Extensive damage if breached, alters sedimentation, upstream floodingExtensive damage if breached, alters sedimentation, upstream flooding Dams (irrigation, hydel, recreation) Dams (irrigation, hydel, recreation) stream profile altered, habitat destroyed, seismic riskstream profile altered, habitat destroyed, seismic risk

Kissimmee River Project Wetlands drained Wetlands drained Dairy Farms and Sugar Plantation moved inDairy Farms and Sugar Plantation moved in Fertilizers and pesticides washed into Florida Bay Fertilizers and pesticides washed into Florida Bay Algal Bloom used up dissolved oxygen in water Algal Bloom used up dissolved oxygen in water Excessive sedimentation smothered bottom communities and blocked sunlight in deeper water Excessive sedimentation smothered bottom communities and blocked sunlight in deeper water Death of corals, sponges and bottom-communities Death of corals, sponges and bottom-communities Loss of habitat of fish and fowls of wetlandLoss of habitat of fish and fowls of wetland Loss of recharge of groundwaterLoss of recharge of groundwater Loss of evaporation and drop in rainfallLoss of evaporation and drop in rainfall Exotic plants moved inExotic plants moved in Now the river is being restored to original channel Now the river is being restored to original channel

Water Quality Most freshwater contain dissolved substances Most freshwater contain dissolved substances concentrations are described in ppm or ppb concentrations are described in ppm or ppb TDS=Total Dissolved Solids TDS=Total Dissolved Solids 500 to 1000 ppm for drinking water500 to 1000 ppm for drinking water 2000 ppm for livestock2000 ppm for livestock some solids (e.g., Iron, Sulfur) more harmful than others (e.g. calcium)some solids (e.g., Iron, Sulfur) more harmful than others (e.g. calcium) synthetic chemicals can be toxic at ppb levelsynthetic chemicals can be toxic at ppb level Radioactive elements pose special hazard Radioactive elements pose special hazard Uranium, Radium, RadonUranium, Radium, Radon